Released on Thursday and powered by a new JavaScript engine, Opera 10.5 beat all comers to easily take the top speed spot.

According to tests run by Computerworld, Opera 10.5 was nearly 15% faster than Safari for Windows and almost 20% faster than Google's Chrome, the previous No. 1 and No. 2 browsers. Opera's preview was more than twice as fast as Mozilla's Firefox 3.6, over eight times faster than Opera 10.10, and 10 times faster than Microsoft's Internet Explorer 8 (IE8).

Computerworld ran the SunSpider JavaScript benchmark suite in Windows XP Service Pack 3 (SP3) three times for each browser, then averaged the scores to arrive at the final rankings.

Opera 10.5 features a new JavaScript rendering engine, dubbed Carakan, and boasts a new vector graphics library called Vega that handles all graphics rendering in the browser. Opera claims that Vega renders graphics about three times faster than the library utilized by Opera 10.10, the company's current production browser.

Other additions to the beta include a revamped interface that reduces the space allotted to menus, support for Windows 7's Aero Peek and Jump List features, an address bar that brings the history and bookmark search of Firefox's Awesomebar to Opera, and the ability to mark any tab as private so there's no record kept of sites visited or actions taken within that tab.

Opera 10.5's beta is available for Windows only, but alpha builds of the Mac and Linux versions can be downloaded from the Opera Desktop Team blog.

The Norwegian browser maker has not set a ship date for the final of 10.5, but has said that the Windows version will beat the others to that milestone as well. About the time that the final code for Windows is released, Opera will have the Mac and Linux betas ready.